Raven,
We need the annuity formula to calculate this.
P = PMT[((1+r)n-1)/r]
PMT = annual contribution
r = annual interest rate
n = number years invested
For James we have
P = 6000 [((1+.05)30-1)/.05] = 398,633
At age 65 before any withdrawals, James will have accumulated $398,633
When he withdraws the money, he'll have to pay 25% in taxes, $99,658 and he'll have a meet of $298,975
For John we have
P = 5000 [((1+.05)30-1)/.05] = 332,194
At age 65 before any withdrawals, James will have accumulated $332,194
P = 5000 [((1+.05)30-1)/.05] = 332,194
At age 65 before any withdrawals, James will have accumulated $332,194
Since John has a Roth IRA, his contributions were already taxed and he owes no tax on the funds he withdraws.
John will net more by
$332194
-298975
----------
$33,219